tr1

Usage

Overview

The tr utility copies the standard input to the standard output with substitution or deletion of selected characters.

The options are as follows:

-C

Complements the set of characters in string1; for instance, “-C ab” includes every character except for ‘a’ and ‘b’.

-c

The same as -C.

-d

The -d option causes characters to be deleted from the input.

-s

After all deletion and translation is completed, the -s option squeezes multiple consecutive occurrences of the characters listed in the last operand (either string1 or string2) into a single instance of the character.

In the first synopsis form, the characters in string1 are translated into the characters in string2 where the first character in string1 is translated into the first character in string2 and so on. If string1 is longer than string2, the last character found in string2 is duplicated until string1 is exhausted.

In the second synopsis form, the characters in string1 are deleted from the input.

In the third synopsis form, the characters in string1 are compressed as described for the -s option.

In the fourth synopsis form, the characters in string1 are deleted from the input, and the characters in string2 are compressed as described for the -s option.

The following conventions can be used in string1 and string2 to specify sets of characters:

character

Any character not described by one of the following conventions represents itself.

\octal

A backslash followed by 1, 2, or 3 octal digits represents a character with that encoded value. To follow an octal sequence with a digit as a character, left zero-pad the octal sequence to the full 3 octal digits.

\character

A backslash followed by certain special characters maps to special values.

\a

<alert character>

\b

<backspace>

\f

<form-feed>

\n

<newline>

\r

<carriage return>

\t

<tab>

\v

<vertical tab>

A backslash followed by any other character maps to that character.

c-c

Represents the range of characters between the range endpoints, inclusively.

[:class:]

Represents all characters belonging to the defined character class. Class names are:

alnum

<alphanumeric characters>

alpha

<alphabetic characters>

blank

<blank characters>

cntrl

<control characters>

digit

<numeric characters>

graph

<graphic characters>

lower

<lower-case alphabetic characters>

print

<printable characters>

punct

<punctuation characters>

space

<space characters>

upper

<upper-case characters>

xdigit

<hexadecimal characters>

With the exception of the “upper” and “lower” classes, characters in the classes are in unspecified order. In the “upper” and “lower” classes, characters are entered in ascending order.

For specific information as to which ASCII characters are included in these classes, see isalnum(3), isalpha(3), and related manual pages.

[=equiv=]

Represents all characters or collating (sorting) elements belonging to the same equivalence class as equiv. If there is a secondary ordering within the equivalence class, the characters are ordered in ascending sequence. Otherwise, they are ordered after their encoded values. An example of an equivalence class might be “c” and “ch” in Spanish; English has no equivalence classes.

[#*n]

Represents n repeated occurrences of the character represented by #. This expression is only valid when it occurs in string2. If n is omitted or is zero, it is interpreted as large enough to extend the string2 sequence to the length of string1. If n has a leading zero, it is interpreted as an octal value; otherwise, it's interpreted as a decimal value.

Exit status

The tr utility exits 0 on success, and >0 if an error occurs.

Examples

The following examples are shown as given to the shell:

Create a list of the words in file1, one per line, where a word is taken to be a maximal string of letters.

$ tr -cs "[:alpha:]" "\n" < file1

Translate the contents of file1 to upper-case.

$ tr "[:lower:]" "[:upper:]" < file1

Strip out non-printable characters from file1.

$ tr -cd "[:print:]" < file1